Purification of substances by chromatography, particularly employing high throughput technologies, is increasingly popular in the area of life science research. Traditionally, purification has been performed using columns containing the chromatography media in gel (slurry) form consisting of discrete beads of the media uniformly dispersed in a selected aqueous buffer. Column-based techniques are desirable from the viewpoint of large binding capacity; however, limitations arise when high throughput is desired since only several columns can be accommodated simultaneously.
To increase throughput, microcentrifuge spin columns, using about 1 ml or less of gel volume, have been used. Speed is thereby increased as is the ability to perform multiple (˜12-24) separations at one time. To achieve higher throughput with similar gel volume, the use of gel dispersed in microtiter-filter plates, such as available from Whatman, Polyfiltronics, has become popular. Using these plates 96 or more purifications can be performed simultaneously.
Several problems, however, are encountered when using microtiter filter plates. The chromatography media tends to settle during dispensing of gel into the discrete wells, thus making it difficult to equalize the volume of media in all wells, particularly when dispensing is performed automatically, e.g., robotically. Also, because the gel is in the form of an aqueous slurry in the wells, it can leak out of the “drip director” or spillover the side walls of the wells, particularly if the gel is dispensed into the wells prior to arrival in the laboratory. A further problem centers on the lack of stability of many gel slurries, especially at room temperature. This results in the inability to store large batches of the gel for extended periods of time for sequent use in multiple purifications and assays.
One final drawback encountered with the use of currently available chromatography gels is that the gel usually must be first washed and then subsequently equilibrated in the aqueous medium (buffer) chosen for the desired application. This, of course, necessitates additional procedural steps for the end user and, accordingly, is time consuming.